What is the Anti-Lock Brake (ABS) Fluid Level Sensor all about?

While your ABS system requires electricity in order to operate, it relies on hydraulic pressure to activate the brakes (as does your regular braking system). Because an ABS system has more intensive fluid needs, such as sending additional fluid to the accumulator for use during actual ABS operation, there needs to be a way to ensure that fluid levels are constantly monitored. This is done by the anti-lock brake (ABS) fluid level sensor, or brake fluid level sensor, if you prefer. The fluid level sensor is exactly what it sounds like. It’s an electronic sensor generally installed in the body of the master cylinder with just one job – to keep an eye on the level of fluid in the reservoir. It is an electrical switch that determines if the fluid is low by a change in electrical resistance. If the fluid level drops below a safe limit, the sensor sends a signal to the computer, which then turns on the ABS light in your dash (and disables ABS).

Keep in mind:

• The anti-lock brake fluid level sensor can fail over time due to a number of problems, but most commonly through a lack of maintenance in terms of fluid changes.
• The fluid level sensor is not inspected during normal maintenance, although the color and level of the brake fluid in the reservoir should be.

How it's done:

• The anti-lock brake fluid level sensor is verified to see if it needs to be replaced
• The defective anti-lock brake fluid level sensor is removed
• The new anti-lock brake fluid level sensor is installed
• The anti-lock brake fluid level sensor is tested for operation
• The vehicle is tested to ensure proper operation of the anti-lock brake fluid level sensor

Our recommendation:

The brake fluid level sensor monitors the level of fluid in the reservoir, and then communicates that information to the brake system computer. The computer determines if the level is safe for operation, and if not, turns the ABS warning light in your dash on, and then disables the ABS system to prevent potential damage. If your ABS light is on, we recommend having the problem diagnosed by one of our expert mechanics immediately.

What common symptoms indicate you may need to replace the Anti-Lock Brake (ABS) Fluid Level Sensor?

• ABS light is on
• ABS system is not functional

How important is this service?

Without a functioning brake fluid level sensor, your braking computer will be unable to determine whether there is enough fluid in the system for safe operation, and will disable the ABS while turning on the brake warning indicator. You may not be able to stop your vehicle in a controlled fashion or you may lock up the brakes on slippery surfaces, potentially causing an accident. Have the anti-lock ABS fluid level sensor replaced if it is faulty.